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COMPANY, OF 1 FFICE.

C. FERGUSON, OF GARDEN CITY, NEW YORK, ASSIGNOR TO NICHOLS COPPER YORK,N. Y., A CORPORATION OF NEW YORK. l J'ATMENT OF ELECTROLYTIC SLIMES.

nearer, I no Drawing." Application filed September 29,

T all whom it may concern of Garden City, Nassau county, New York, 4

have invented certain new and useful Imrovements in the Treatment ofElectrolytic glimes, of which the following 1s a specification.

My invention relates particularly to the treatment of slimesjsuchasthose obtained in the electrolytic refining of metals, as, for

instance, copper, though it maybe applied to others, such as thoseobtained 1n the manufacture of blue vitriol and similar slimes or muds.These slimes generally contain gold, sillver, cop er selenium,tellurium, arsenic, antimony, lead and silica in varying proportions andsometimes contain also traces of bismuth, nickel and iron.

The particular slime, to which the process is particularly applicable,is that resulting from the electrolytic refining of crude metalliccopper, that is to say, bessemeriaed copper matte. A typical analysis ofthis material (in the dry state) is as follows:

Copper 27.47% Silver 16.97 Gold .39 Selenium and tellurium 10.40 Arsenic1.72 Antimony .44 Silica 25.

' Lead sulfate 2 Bismuth, nickel, iron, etc Traces In this sample, thecopper was mostly in the form of metallic copper, the silver was mostly'tellurid andv selenid, and the gold 4 principally tellurid.

The object of my invention is to so treat slimes of the kind specifiedthat the values, gold, silver and copper are extracted in a commerciallpracticable and economical manner. ore 'articularly T aim to producefromthe-slimes, pure gold and silver and copper sulfate, (or metalliccopper if Speciflcation of Letters latent.

Patented June 3, 1919.

1915, Serial No. 53,178. Renewed October 26, 1918. Serial Ho. 259,352.

ployed, possessing many valuable advantages thereover, and comprisingthe following steps First, roasting the slime in the presence of asulfatizin agent to the point where substantially all of the silver isconverted into sulfate, and a part of the copper remains in the form ofsulfate, and another part remains in the form of oxid. During thisoperation a considerable part of selenium, tellurium, arsenic, lead andbismuth are volatilized from the slime. During this step the losses ofprecious metal values are extremely small.

Secondly, lixiviating or leaching with a suitable solvent for certainportions of the roasted slime (particularly the silver sulfate andcopper sulfate) and thereafter extracting by suitable methods, the metalvalues contained in the leached residue.

When treating a slime or mud of the kind 1above described I preferablyproceed as folows:

The mud is roasted at a suitable roasting temperature preferably at atemperature of from 500 C. to 600 C. in the presence of a sulfatizingagent such as sulfuric acid or a sulfate, such as copper sulfate or ironsulfate. The sulfatizing agent is employed in sulficient amount tosulfatize not merely the copper, but also the silver. The roasting iscarried out in the presence of air, so that instead of the abovecompounds containing the sulfuric acid radical, any other compound suchas sulfur dioxid or trioxid or a sulfid, as pyrites, which under theconditions will produce a compound containing such radical and willeffect a sulfatizi action, may be used as sulfatilzing agent. lheroasting operation is designed to produce a substantially completeoxidation of the mud, and this may require a roasting period of abouthours. The roasting is so carried out, preferably, that substantiallyall of the silver is transformed into silver sulfate, the copper beingpartly in the form of oxid and partly in the form of sulfate.

- During the roastin operation the whole, or usually, a part of t eselenium, tellurium and arsenic goes 0]? in gaseous form. The roastedslime is now lixiviated preferably with water by which almostall of thesilver together with a part of the copper and. possibly traces ofselenium,tellurium, arsenic and antimony are separated in soluble formfrom the solid residue containing the other waterinsoluble constituents.

The thus produced silver solution which may contain 94% of the silverand 20 to of the copper of the original slime may be treated in anyknown manner for the separation and removal of the silver and copper,that is, for the extraction of the metal values therein. For example, itmay be treated so as to produce silver precipitated on copper in theform of silver cement.

The solid residue, above mentioned, resulting from the lixiviation withWater 1s now lixiviated with a dilute acid, such as sulfuric acid,whereby there is produced a second solid residue containing the acidinsoluble constituents and a solution which contains substantially allof the copper content of the first solid residue, a very smallpercentage of silver and possibly some selenium, tellurium, arsenic andantimony.

This second solution, which may contain to 25% of the copper and 3% ofthe silver of the original slime and may be termed the copper solution,may be treated in any suitable manner for the extraction of its values.For example it may be treated to form cement silver and the co persulfate solution made into blue vitriol: or electrolyzed to formelectrolytic copper or passed over iron to form cement copper.

The second solid residue resulting from the acid treatment, containingall of the gold of the original mud and substantially no copper, may besubjected to any suitable treatment for the extraction of the gold.Preferably the goldis dissolved out by any gold solvent, in which caseit is advantageous to use chlorin or a chlorin compound, such as aquaregia, which may be made from sulfuric acid, sodium nitrate and sodiumchlorid. Bythis treatment practically all of the gold is obtained in thesoluble form of gold chlorid. The gold solution may be treated, ifdesired, with a-reducing agent, such as eopperas or ferrous sulfate, orsulfur dioXid, to precipitate the gold in the form of metal which may berefined by conventional methods. The residue resulting from the a uaregia treatment, which may be termed t e third residue, contains smallpercentages of silver and gold, for example 2 to 3% of the silver of theoriginal mud, mostly in the form of chlorid, and .75% of the originalgold, and is treated. with a solvent for silver, preferably sodiumhyposulfite; this dissolves practically all of the silver and a littleof the gold. The silver and gold are now recovered from the hyposulfitesolution in any known way. The final residue resulting from thehyposulfite treatment is available for use in ore smelting or metalrefining furnaces.

Instead of lixiviating first with Water and then with acid, as describedabove, it may be advantageous in some cases, especially- When theselenium, tellurium, arsenic and antimony contents of the original slimeare relatively small, to omit the water lixivia- 'tion and employ onlythe acid lixiviation.

In this case the silver and copper are obtained as sulfates in thesolution, and the solid residue is similar to the second solid residueabove described. In either case the original mud or slime is roastedwith a sulfatizing agent, and then lixiviated with a solvent ,forcertain of the ingredients of the sulfatized product.

The temperatures and the strengths of the various solutions and the timeof treatment will, of-course, vary. with the different requirements, butsuch details of operation are well within the province of anyone skilledin the art. If no gold were present in the original mud the stage of theprocess dealing with gold would, of course, be omitted. If the secondresidue is substantially free from silver and copper, the chlorintreatment might be omitted and the residue subjected to refining merely.

I claim:

1. The herein described process of treating electrolytic copper refineryslimes containing silver, but not containing material quantities ofsulfur which comprises roasting the same in the presence of an addedsulfatizing agent, until at least the major part of the silver isconverted to silver sulfate, and thereafter leaching the roastedmaterial.

2. The herein described process of treating the slimes produced in theelectrolytic refining of metallic copper, which slimes consistessentially of copper, silver, gold, se-

lenium, tellurium, arsenic, antimony, silica and lead sulfate, togetherwith traces of hismuth, nickel, iron and the like, which slimes do notcontain any considerable quantities of sulfur, which comprisessubjecting the said slimes, in thepresence of an added sul-' fatizingagent to a roasting operation, and thereafter leaching whereby the bulkof the silver present is obtained in the solution and wherebysubstantially all of the gold is left in the undissolved residue.

3. The herein described process of treating slimes containing gold,silver and copper, which comprises subjecting such slime to a roastingoperation in the presence of a sulfatizing agent, whereby a silver and apart of the copper are converted into sulfates, separating the silverand copper from the gold-bearing residue by leaching the roastedmaterial with a solvent for the silver and copper, recovering the silverand copper from the solution thereof, and recovering the gold from thegold-bearing residue.

4. The herein described process of treating slimes which comprisessubjecting slime to a roasting operation in the presence of asulfatizing agent, treating the roasted slime with water to producewater-soluble and Water-insoluble portions, extracting the metal valuesfrom said water-soluble portion, treating said Water-insoluble portion.With an acid to produce acid-soluble and acid-insoluble portions, andextracting the metal values from said acid-soluble and acid-insolubleportions.

5. The herein described process of treatingslimes which comprisessubjecting slime to a roasting operation in the presence of asulfatizing agent, treating the roasted slime With Water to produceWater-soluble and Water-insoluble portions, extracting the metal valuesfrom said water-soluble portion, treating said water-insoluble portionwith sulfuric acid to produce acid-soluble and acid-insoluble portions,and extracting the metal values from said acid-soluble andacid-insoluble portions.

6. The herein described process of treating slimes whichcomprises-subjecting slime to a roasting operation in the presence of asulfatizing agent, treating the roasted slime with water to producewater-soluble and Water-insoluble portions, extracting the metal valuesfrom said water-soluble portion, treating said water-insoluble portionwith an acid to produce acid-soluble and acid-insoluble portions,extracting the metal values from said acid-soluble portion, treatingsaid acid-insoluble portion with a solvent for gold to produce a goldcontaining solution and an insoluble residue, and extracting the metalvalues from said solution and said residue.

7. The herein described process of treat-' ing slimes containing gold,silver and copper, which comprises subjecting such slime to a roastingoperation in the presence of a sulfatizing agent, treating the roastedslime with a solvent for substantially all of the silver and copper inthe roasted slime whereby a soluble portion containing silver and copperand an insoluble portion containing the gold are produced, andextracting the metal values from said soluble and insoluble portions.

8. The herein described process of treating slimes containing gold,silver and copper, which comprises subjecting such slime to a roastingoperation in the presence of a sulfatizing agent, treating the roastedslime with Water, whereby a water-soluble portion containing part of thesilver and copper and a water-insoluble portion containing the gold areproduced, treating said Water-insoluble portion with sulfuric acidwhereby an acid-soluble portion containing substantially the Whole ofthe silver and copper of said water-insoluble portion and anacid-insoluble portion containing the gold are produced, and extractingthe metal values from said waterand acid-soluble portions and from saidacid-insoluble portion.

9. The herein described process of treating slimes containing gold,silver and copper, which comprises subjecting such slime to. a roastingoperation in the presence of a sulfatizing agent, treating the roastedslime with water, whereby a water soluble portion containing part of thesilver and copper and a water-insoluble portion containing the gold areproduced, treating said Water-insoluble portion with sulfuric acid,whereby an acid-soluble portion containing substantially the whole ofthe silver and copper of said water-insoluble portion and anacid-insoluble portion containing the gold are produced, extracting themetal values from said Waterand acid-soluble portions, treating saidacid-insoluble portion with a gold solvent to produce a gold containingsolution and an insoluble residue, and extracting the metal values fromsaid solution and said residue. x

10. The herein described process of treat ing slimes produced in theelectrolytic refining of metal which comprises roasting the same in thepresence of an added sulfatizing agent until sulfates of the metal havebeen formed in substantial quantities. In testimony whereof I havehereunto set WILLIAM C. FERGUSON.

' my hand.

